Variable reactance transformer



Feb. 24, 1942. TYRNER 2,274,015

VARIABLE REACTANGE TRANSFORMER Filed Nov. 2, 1940 5 Sheets-Sheet l ATTORNEYS.

Feb. 24, 1942. J TYRNER 2,2 74,015

VARIABLE REACTANCE TRANSFORMER Filed Nov. 2, 194g 5 Sheets-Sheet 2 INVENTOR.

ATTORNEYS Feb. 24, 1942. J. TYRNER VARIABLE REACTANCE TRANSFORMER Filed Nov. 2, 1940 5 Sheefs-Sheet s Feb. 24, 1942.

J. TYRNER VARIABLE REACTANCE TRANSFORMER Filed Nov. 2, 1940 5 Sheets-Sheet 4 m ,5 nu n1 HIH IIHHHI ATTORNEKF Feb. 24, 1942. J. TYRNE R VARIABLE REACTANGE TRANSFORMER 5 Sheets-Sheet 5 Filed NOV. '2, 1940 A TTORNEKS Patented Feb. 24, 1942 UNITED STATES PATENT OFFICE Claims.

The present invention relates to transformers of the type employing movable windings for varying their reactance.

The large forces prevailing in such transformers have hitherto made it dimcult to construct them for heavy current duty, and an important object of the invention is to provide a construction of variable-reactance transformer adaptable without difiiculty to any current duty desired.

Another object of the invention is to provide a variable-reactance transformer the reactance of which is uniformly varied over a wide range. Still another object of the invention is to provide a variable-reactance transformer which is simple in construction and low in cost of manufacture. A further object of the invention is to minimize the vibration or chattering which is liable to occur in transformers having movable windings.

In my copending application Serial No. 352,680, filed August 15, 1940, there is disclosed a transformer construction comprising a pair of axially aligned magnet rings, between which are disposed at intervals about their axis an even number of parallelly extending magnet columns. The transformer windings in this transformer construction are equal in number to the magnet columns, but are arranged in pairs alternately embracing one-half of the magnet columns, each of such pairs consisting of a fixed winding and a movable winding. The fixed windings are so positioned that they all align with one another, preferably in abutting relation to one of the magnet rings, while the movable windings are all adjustable together in one direction toward the fixed windings and in the other direction away from the fixed windings. This transformer construction makes possible a wide range of reactance variation by reason of the close spacing permitted between adjacent magnet columns. However, the fixed windings are preferably made larger than the movable windings to adapt the movable windings for movement into and out of the fixed windings, and while this reduces the upper limit of reactance variation by increasing the spacing between adjacent magnet columns, the leakage flux corresponding to the extreme position of adjustment of the movable windings within the fixed windings is made practically nil, which considerably reduces the lower limit of reactance variation and therefore more than compensates for the reduced upper limit.

The transformer construction of the present invention makes use of the magnet rings and former construction, but is an improvement as regards its transformer winding arrangement. The magnet columns are again even in number and exceed two. but the transformer windings are now twice the number of the magnet columns, are all preferably made of the same size, and embrace all magnet columns, each of which is provided with a fixed winding and a movable winding. The fixed windings are staggered on the various magnet columns so as to alternate with one another on either side of a median plane intermediate the two magnet rings, while the movable windings are inversely staggered with respect to the fixed windings and therefore constitute two groups, one of which is movable into and out of the spaces formed by the fixed windings on one side of said median plane and the other of which is movable into and out of the spaces formed by the fixed windings on the other side of said median plane, the two groups being adapted for simultaneous movement in opposite directions toward and away from said median plane. This novel arrangement of the transformer windings, in the transformer construction of the present invention, provides the following advantages:

First to be noted is the fact that the close clustering of the various windings, obtained with the movable windings in their innermost positions of adjustment within the intermediate staggered spaces provided by the fixed windings, has practically the same minimizing effect on flux leakage as is produced in the aforestated prior transformer construction by a nesting of the movable windings within the fixed windings. There is thus no need for enlarging the size of the fixed windings in the transformer construction of the present invention, which makes possible a close spacing between adjacent magnet columns in spite of the absence of intermediate columns carrying no windings. It is clear that the larger number of transformer windings employed in the transformer construction of the present invention, in proportion to the number of magnet columns, permits transformers of increased current capacity to be more economically made without narrowing their desired range of reactance variation.

Moreover, the movable windings, by their movement into and out of the intermediate staggered spaces provided by the fixed windings, effect a much more uniform reactance variation than is capable of being obtained by the aforestated prior transformer construction. In the magnet columns of the aforestated prior trans- 00 latter construction, the movable windings effect but a slight variation in the leakage flux as long as they are moved in either direction of adjustment within the fixed windings, but cause such flux to undergo an abrupt change coincident to their passage into or out of the fixed windings. This abrupt change in fiux leakage is effectively eliminated in the transformer construction of the present invention, the movable windings of which vary the leakage flux substantially uniformly from their innermost positions of minimum leakage. This more uniform reactance variation obtained in the transformer construction of the present invention is, of course, an advantage in itself. In addition, it appreciably reduces the mechanical forces exerted on the movable windings, which is evident from the reduced rate of energy change per unit distance of movement of such windings,

Another advantage provided by the transformer winding arrangement of the transformer construction of the present invention is due to the substantially equal forces respectively exerted on the two groups of movable windings. Except for slight manufacturing discrepancies, these forces balance one another, which is effective in minimizing the vibration or chattering inherent in the movement of the movable windings as a whole.

Still another advantage provided by the transformer winding arrangement of the transformer construction of the present invention is the minimized copper loss obtained by making all transformer windings of the same size.

The invention will be understood from the following description taken in conjunction with the accompanying drawing in which Fig. l is a view in front elevation of a transformer embodying the invention, with its casing removed; Fig. 2 is a section taken on the line 22 of Fig. 1; Fig. 3 is a section taken on the line H of Fig. 2; Fig. 4 is a view of the transformer as seen in the direction of the arrow 4 in Fig. 2; Figs. 5 to 7 are schematic views particularly illustrating the leakage flux variation effected by the windings on any two adjacent magnet columns, the movable windings being shown in three different positions, respectively; and Fig. 8 is a wiring diagram showing an arrangement of switches which may be used to adapt the transformer to different current output ranges.

Referring particularly to Figs. 1, 3 and 4, upper and lower cylindrical castings ll serve as the supports for upper and lower magnet rings l2. Each of the supporting castings H is provided with an inwardly projecting annular flange Ha; and each of the magnet rings I2 is constructed by winding a band of magnetic material on the flange I la of its respective supporting casting II. This construction of the two magnet rings I! is facilitated by upper and lower centrally apertured guide plates l4 rigidly secured to the two supporting castings Ii around their annular flanges Ila, as by welding. The two magnet rings 12 contact with these guide plates, the outer edges of which may conveniently take the form of a square, which is purposely made large to permit varying the outer diameter of the two magnet rings I2. The two bands of magnetic material forming the two magnet rings I! may be prevented from uncoiling by welding their outer ends to the convolutions underneath. Suitable base members l5 are secured by welding or otherwise to the lower plate ll. Centrally mounted for rotation in the upper and lower castings II, is a right and left hand threaded shaft ll provided at its upper end with an operating crank H.

The embodiment of the invention shown in the drawing comprises four magnet columns, which are disposed at intervals about the axis of the shaft l6 and contact at their ends with the two magnet rings l2. As best shown in Fig. 2, each of the four magnet columns comprises two rectangular legs 20 adapted to form the letter V in cross-section by setting them at an angle to one another and is positioned so that the angle between the two legs 10 diverges away from the axis of the shaft ll. Generally stated, this angle is preferably chosen so that the adjacent legs of any two magnet columns are spaced parallel to one another. which condition is obtained by a 90 angle in the embodiment of the invention shown in the drawings.

Each of the two legs Ill forming any of the four: magnet columns may be made up of rectangular laminations of uniform size extending cross-wise to the longest cross-sectional leg dimension, as shown in Fig. 2. As a lamination clamping means for each of the four-magnet columns, a' single inner vertical angle member 2| set to contact with both legs of the column is used in conjunction with two outer vertical angle members 22 each of which is set to contact with one leg. The two outer members 22 of each clamping means are rigidly connected to one another by welding them to a saddle-shaped member II; and bolts 28 passing through holes in the members 24 and II serve to draw the two outer members 22 toward the single inner member 2|. Each of the four magnet columns thus constitutes a unitary structure capable of independent assembly. As best shown in Fig. 3, upper and lower bolts 26 welded to each of the angle members I! extend through openings in the magnet rings It, the plates l4 and the upper and lower castings l I, whereby each of the four magnet columns is held in place-between the magnet rings II which are themselves held against their adiacent plates I4.

The embodiment of the invention shown in the drawings comprises a total of eight transformer windings consisting of four fixed (secondary) windings Ii to 34, and four movable (primary) windings I! to 3!. As will be noted, the eight windings are arranged in pairs respectively embracing the four magnet columns, each pair consisting of a fixed winding and a movable winding. Each of the eight windings is of the same size and substantially triangular-shaped, with the view to minimizing the spacing between any two adjacent magnet columns.

As shown, the four fixed (secondary) windings II to II are staggered on the four magnet columns to alternate with oneanother on either side of a horizontal plane midways between the two magnet rings II. The fixed windings If to 34 at their inner portions are clamped against the vertical members 2| by U-shaped bolts ll (Fig. 8) car ym nuts 4|; it being understood that legs of said bolts pass through holes in the vertical members II and in the saddle-shaped members 24 which are welded to the corresponding vertical members 22. In addition, the windings ll to 34 may be held against displacement by straps 42 passing around said coils and secured to angle irons ll welded to the vertical members 22, as best shown in Fig. 4.

The four movable (primary) windings ll to ll are inversely staggered on the four magnet columns so as to constitute a group of two windings (II and I1) movable into and out of the two spaces formed by the four ii'xed windings II to 3'4 on one side of the aforestated central plane, and another group of two windings ill and a) movable into and out of the two spaces formed by the four fixed windings ll to It on the other side of the aforestated central plane. These two groups of movable windings are mounted on separate spiders M respectively threaded on the right and left hand threaded portions of the shaft II. The shape of these spiders is shown in Fig. 2 from which it will be evident that each spider 44 comprises a central portion from which extend two pairs of complementary arms 45. Each pair of movable windings is secured to a pair of arms l! of one of the spiders 44 and to the central portion of that spider. The securing means for this purpose comprises straps 46 which pass around the winding and are secured to the ends of the spider arms II in any suitable manner; while the inner portion of the winding is secured to the hub portion of the spider by means of a strap 41 which passes around the winding and is secured in any suitable manner to the hub of the spider. Thus the windings of each movable pair of windings are secured to and move with a spider.

Referring particularly to Fig. 3, each spider 44 has vertically secured thereto a number of bolts 49 and has spaced therefrom on the shaft It a nut-member 50 formed with appropriate openings for free passage therethrough of the bolts 49, compression springs II being provided on the bolts 40 below the nut-member 50. In the case of each spider 44, these springs function to force the spider 44 and its nut-member 50 toward one another and to thus take up any tendency of loose play of either a spider N or its nut-member 50 on the shaft it. While this alone is effective in minimizing vibration,- it should be noted that the forces exerted by the fixed windings on the two groups of movable windings resolve into equal and opposite forces on the two spiders 44, which is also eifective in minimizing vibration because the balancing of the forces on the two groups of movable windings insures against longitudinal oscillatory movement of the shaft l6. Obviously, the shaft It operates through its right and left-hand threaded portions to move the two spiders 44 and the attached two groups of movable windings in opposite directions into and out of the four spaces provided by the fixed windings, the two groups of movable windings being capable of movement out of such spaces to their extreme limits of travel adjacent the two magnet rings i2. Rotational displacement of the two spiders ll may be prevented by horizontal strips 52 of insulating material bolted thereto and adapted to ride freely on vertical rods "passing through and bolted to the two plates ll.

In transformers of the type to which the presentinvention relates, the primaries are made of smaller wire than the secondaries. Therefore, in the embodiment of the invention shown in the drawings, it is preferred to use the movable windings 3' to 38 as the primaries and the fixed windings II to 34 as the secondaries. However, this is not essential, since it is possible to use the fixed windings 3| to 34 as the primaries and the movable windings 35 to ll as the secondaries. Obviously, the transformer flux established by the combined action of the various windings, travels in opposite directions through any two adjacent magnet columns.

practically nil. As the movable windings P.

move out of their innermost positions, however, more and more space is provided for leakage flux, which consequently increases more and more. In Fig. 6, the movable windings P are shown as having passed just beyond the fixed windings S, the leakage flux having then attained an appreciable value. In Fig. 7, the movable windings P are shown in their outermost positions, the leakage flux being a maximum, and a maximum of considerable value because of the close spacing of the magnet columns. As will readily be appreciated, this leakage flux variation is substantially uniformly effected between the innermost and outermost positions of the movable windings P.

In accordance with the invention, transformers of high current capacity may be made without difllculty.

Fig. 8 shows a switching arrangement which may be used to adapt a heavy current duty transformer to three different current output ranges. This transformer is assumed to be constructed in accordance with the described embodiment of the invention, which comprises four primaries II to It and four secondaries It to 38. The four primaries II to II are adapted to be connected in parallel with one another to the source, while the four secondaries 35 to 38 are adapted to be connected in parallel with one another to the load. However, a switch A is provided in the circuit to the two primaries l5 and 31; a switch B is provided in the circuit to the corresponding secondaries II and I3; and a switch C is provided in the circuit to the secondary 32. With the three switches A, B and C closed, all four primaries 3| to 34 and all four secondaries 35 to SI are working, which adapts the transformer to heavy-current duty. With the two switches A and B open and the switch C closed, only two primaries 38 and I l and only two secondaries 32 and u are working, which adapts the transformer to intermediate-current duty. With all three switches A, B and C open, only the primary 3! and its associated secondary 34 are working, which adapts the transformer to light-current duty, the primary 3' connected to the source being merely idling, it being noted that the primary 3! is once removed on a magnet column from the working primary 38.

It is to be understood that the inventon is not limited to the particular embodiment shown in the drawings, which embodiment may be modifled in various ways without departing from the spirit of the invention.

1. A transformer comprising a pair of magnet rings disposed in axial alignment with one another, an even number exceeding two of magnet columns extending parallel to one another between said magnet rings and disposed at intervals about their axis, fixed windings respectively embracing said magnet columns, movable windings respectively embracing said magnet columns, said flxed windings being staggered on said magnet columns to alternate with one another on either side of a median plane intermediate said two magnet rings, said movable windings being inversely staggered on said magnet columns to constitute two groups one of which is movable into and out the spaces iormed by said fixed windings on one side 01' said median plane and the other of which is movable into and out of the spaces formed by said fixed windings on the other side of said median plane, and means for simultaneously moving said two movable windlng groups in opposite directions toward and away from said median plane.

2. A transformer comprising a pair 0! magnet rings disposed in axial alignment with one another, an even number exceeding two oi magnet columns extending parallel to one another between said magnet rings and disposed at intervals about their axis, fixed windings respectively embracing said magnet columns, movable windings respectively embracing said magnet columns, said fixed windings being staggered on said magnet columns to alternate with one another on either side or a median plane intermediate said two magnet rings, said movable windings being inversely staggered on said magnet columns to constitute two groups one or which is movable into and out of the spaces formed by said fixed windings on one side of said median plane and the other of which is movable into and out 01 the spaces formed by saidfixed windings on the other side of said median plane, and means for simultaneously moving said two movable winding groups in opposite directions toward and away from said median plane comprising spiders upon which said two movable winding groups are supported and a right and left-hand threaded shaft cooperating with said spiders.

3. A transformer comprising a pair of magnet rings disposed in axial alignment with one another, an even number exceeding two of magnet columns extending parallel to one another between said magnet rings and disposed at intervals about their axis, each of said magnet columns consisting of two rectangular legs set at an angle to one another to form the letter V in cross-section and being positioned to cause said angle to diverge away from the axis of said two magnet rings, said angle being chosen to cause the adjacent legs or any two adjacent magnetcolumns to be spaced parallel to one another, fixed windings respectively embracing said magnet columns, movabl windings respectively embracing said magnet columns, said fixed windings being staggered on said magnet columns to alternate with one another on either side of a median plane intermediate said two magnet rings, said movable windings being inversely staggered on said magnet columns to constitute two groups one of which is movable into and out or the spaces iormed by said fixed windings on one side or said median plane and the other of which is movable into and out of the spaces formed by said fixed windings on the other side or said median plane, and means for simultaneously moving said two movable winding groups in opposite directions toward and away from. said median plane.

4. A transformer comprising a pair of magnet rings disposed in axial alignment with one another. tour magnet columns extending parallel to one another between said magnet rings and disposed at intervals about their axis, each of said magnet columns consisting of two rectangular legs set at a right angle to one another in crosssection and being positionedto cause said angle to diverge away from the axis or said magnet rings, tour fixed windings respectively embracing said magnet columns, tour movable windings respectively embracing said magnet columns, said fixed windings being staggered on said magnet columns to alternate with one another on either side or a median plane intermediate said two magnet rings, said movable windings being inversely staggered to constitute two pairs one of which is movable into and out o! the spaces formed by said fixed windings on one side of said median plane and the other of which is movable into and out o! the spaces formed by said fixed windings on the other side of said median plane, and means for simultaneously moving said two pairs of winding groups in opposite directions toward and away from said median plane.

5. A transformer comprising a pair of magnet rings disposed in axial alignment with one another, iour magnet columns extending parallel to one another between said magnet rings and disposed at intervals about their axis, tour fixed windings respectively embracing said magnet columns, tour movable windings respectively embracing said magnet columns, said fixed windings being staggered on said magnet columns to alternate with one another on either side of a median plane intermediate said two magnet rings, said movable windings being inversely staggered to constitute two pairs one of which is movable into and out o! the spaces formed by said fixed windings on one side of said median plane and the other or which is movable into and out of the spaces formed by said fixed windings on the other side of said median plane, and means tor simultaneously moving said two pairs of winding groups in opposite directions toward and away from said median line.

JOSEPH TYRNER. 

